November 2012 SJRWMD Update

The Bigclaw Snapping Shrimp

The bigclaw snapping shrimp is arguably the closest thing to an Indian River Lagoon denizen, seemingly gifted with superpowers.

One of 11 species of snapping shrimp in the lagoon, the bigclaw
snapping shrimp (Alpheus heterochaelis) is the largest and most
colorful member of the pistol shrimp family in the southeastern United
States. A mere two inches in length, the bigclaw is typically a
translucent green hue, marked by bright orange and blue along its legs,
claws and tip of the tail.

Bigclaws are easily identified by the greatly enlarged snapping claw,
used in displays of threat to other snapping shrimp, self defense, and
most important, in stunning and killing prey. The snapping claw of the
bigclaw may grow to half its total body length and is located on either
arm of the body.

The bigclaw’s diet isn’t remarkable. It subsists primarily on a variety
of worms, small fishes and other crustaceans. However, it is the actual
feeding behavior of the bigclaw snapping shrimp that has made it a
superpower. While the concussive force generated by its claw snap is
sufficient to stun or kill small prey at close distance, the snaps
produced by large shrimp are strong enough to break small glass jars or
even aquarium glass.

It was believed that the sound was produced by the rapid closing of the
claw in motion. However, high-speed imaging has revealed a number of
surprising findings. Snapping is accomplished by a shrimp’s cocking
open the moveable part of its claw, referred to as the “plunger,” and
building tension in a second muscle. When this muscle contracts, the
plunger snaps into a socket in the fixed portion of the claw, an action
among the fastest ever recorded in the animal kingdom. A jet of water
is displaced from the socket and released at speeds of up to 62 miles
per hour, producing a cavitation bubble capable of killing nearby prey.

The bubble is extremely short-lived and collapses by imploding within
300 microseconds of formation. The implosion produces not only a
snapping sound, but also a brief and intense flash of light. Analysis
of shrimp bioluminescence, or shrimpoluminescence as it has been dubbed
by researchers, revealed that extreme pressure and temperature
conditions exist at the time of bubble collapse, with one author
indicating that temperatures around the cavitation bubble is about
5,000 degrees Kelvin (or 8,540 degrees Farenheit).

The bigclaw snapping shrimp is a large and colorful shrimp whose claw snap can break a small jar or even aquarium glass.